Numerical analysis of compression mechanics of highly polydisperse granular mixtures with different PSD-s

Wiącek, Joanna; Molenda, M.

doi:10.1007/s10035-018-0788-z

Cited by 8 publications

(6 citation statements)

References 39 publications

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“…11, we observe that a c gradually drops as S increases. Such a phenomenon is also observed during the compression of polydisperse packings in 2D [50] and 3D [51] simulations. As some grains can be accommodated between the bigger ones, the angular distribution becomes relatively more homogeneous.…”

Section: Contact Anisotropysupporting

confidence: 54%

Microstructural analysis of sheared polydisperse polyhedral grains

2020

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This article presents an analysis of the shear strength of numerical samples composed of polyhedra presenting a grain size dispersion. Previous numerical studies using, for instance, disks, polygons, and spheres, have consistently shown that microstructural properties linked to the fabric and force transmission allow granular media to exhibit a constant shear resistance although packing fraction can dramatically change as a broader grain-size distribution is considered. To have a complete picture of such behavior, we developed a set of numerical experiments in the frame of the discrete element method to test the shear strength of polydisperse samples composed of polyhedral grains. Although the contact networks and force transmission are quite more complex for such generalized grain shape, we can verify that the shear strength independence still holds up for 3D regular polyhedra. We make a particular focus upon the role of different contact types in the assemblies and their relative contributions to the granular connectivity and sample strength. The invariance of shear strength at the macroscopic scale results deeply linked to fine compensations at the microstructural level involving geometrical and force anisotropies of the assembly.

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Section: Contact Anisotropysupporting

confidence: 54%

Microstructural analysis of sheared polydisperse polyhedral grains

2020

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“…Unlike the typical nonlinear e‐p curves obtained from laboratory, the void ratio obtained from the simulations linearly decreases with the increase of the mean stress for all samples. The linear e ‐ p relation was also consistently revealed in three‐dimensional DEM simulations of isotropic compression tests 9,62 and confined compression tests 13,33 . This phenomenon could be attributed to the lack of particle breakage in the simulations.…”

Section: Resultssupporting

confidence: 62%

“…With the ability to precisely control grain‐scale properties, particle‐based numerical methods, such as the distinct element method (DEM) 29 and the contact dynamics method, 30,31 appear as powerful and economic tools to study gradation‐dependent behavior of materials. Many numerical studies have been dedicated to revealing the effects of polydispersity on some aspects of deformation behavior of granular materials, such as packing, 6,32 laterally‐confined compression, 13,33 and small strain stiffness 22 . These simulations typically adopted materials with narrow gradations and limited shapes of the GSD curve.…”

Section: Introductionmentioning

confidence: 99%

“…The reason for this difference could be due to the fact that the numerical studies are mostly focused on materials with relatively narrow gradations to reduce the computational cost, and therefore fail to reveal behaviors of materials with wide gradations. In addition, the gradation‐property relationships are overshadowed by the adoption of limited shapes of GSDs, 8,33,39 given that pronounced gradation‐dependence has been found in the simulations using a wide range of GSDs 9,15 …”

Section: Introductionmentioning

confidence: 99%

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Relationships between gradation and deformation behavior of dense granular materials: Role of high‐order gradation characteristics

Liu

Deng

et al. 2021

Num Anal Meth Geomechanics

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This paper numerically investigates deformation behavior of coarse‐grained granular materials with emphasis on the effect of grain size distribution (GSD). Biaxial compression tests are simulated in two dimensions using distinct element method (DEM) on a set of samples composed of uncrushable spheres following a wide variety of GSDs. The results prove that high‐order characteristics of gradation, such as the shape of the GSD curve, significantly affect deformation behavior of widely‐graded materials. Two grading indices are proposed to consider the combined effects of the spread and the shape of the GSD curve, and they are highly correlated with the parameters of the materials’ internal fabric. Strong correlations are found between the proposed grading indices and deformation parameters, such as those of the normal compression line and the critical state line (CSL) in the e‐p space, and the deformation modulus. In contrast, using the more conventional coefficient of uniformity cannot reach effective gradation‐dependent relations for those deformation parameters due to the deficiency in characterizing high‐order features of gradation. This study suggests the need for incorporating high‐order characteristics of gradation into a refined measure of size polydispersity in order to establish gradation‐dependent relations of deformation parameters widely effective for polydisperse granular materials.

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“…Samples containing different particles sizes (polydisperse) have been extensively analyzed [6,[14][15][16][17][18][19][20], showing some counterintuitive results such as the independence of the macroscopic friction with respect to the grain size span [21,22], the shape of the GSD [23,24], and stiffness and Poisson's ratio of the particles [25,26].…”

Section: Introductionmentioning

confidence: 99%

Effects of particle shape mixture on strength and structure of sheared granular materials

2019

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To cite this version:Theechalit Binaree, Itthichai Preechawuttipong, Emilien Azéma. Effects of particle shape mixture on strength and structure of sheared granular materials.Using bi-dimensional discrete element simulations, the shear strength and microstructure of granular mixtures composed of particles of different shapes are systematically analyzed as a function of the proportion of grains of a given number of sides and the combination of different shapes (species) in one sample. We varied the angularity of the particles by varying the number of sides of the polygons from 3 (triangles) up to 20 (icosagons) and disks. The samples analyzed were built keeping in mind the following cases: (1) increase of angularity and species starting from disks; (2) decrease of angularity and increase of species starting from triangles;(3) random angularity and increase of species starting from disks and from polygons. The results show that the shear strength vary monotonically with increasing numbers of species (it may increase or decrease), even in the random mixtures (case 3). At the micro-scale, the variation in shear strength as a function of the number of species is due to different mechanisms depending on the cases analyzed. It may result from the increase of both the geometrical and force anisotropies, from only a decrease of frictional anisotropy, or from compensation mechanisms involving geometrical and force anisotropies.

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Numerical analysis of compression mechanics of highly polydisperse granular mixtures with different PSD-s

Cited by 8 publications

References 39 publications

Microstructural analysis of sheared polydisperse polyhedral grains

Microstructural analysis of sheared polydisperse polyhedral grains

Relationships between gradation and deformation behavior of dense granular materials: Role of high‐order gradation characteristics

Effects of particle shape mixture on strength and structure of sheared granular materials

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